The probe found widespread noncompliance and violations of federal law in how health plans and insurers cover mental health care, echoing the findings of a recent ProPublica investigation.

Health plans, and the companies that administer them, have excluded key behavioral treatments, such as therapies for substance use and autism, and offered inadequate networks of mental health providers, according to a 142-page report released Jan. 17 in conjunction with the Treasury and Health and Human Services departments.

The report, which the agencies are required to file regularly to Congress, also detailed the results of secret shopper surveys of more than 4,300 mental health providers listed in insurance directories and found an “alarming proportion” were “unresponsive or unreachable.” Such error-ridden plans, commonly known as ghost networks, make it harder for patients to get the treatment they need, ProPublica has previously found.